An open candle flame observes the basic physics in which its flame is seen as the visible, gaseous part of a fire. It is caused by a highly exothermic reaction taking place in a thin zone. When the candle is lighted, the fuel molecules in the candle wax are allowed to vaporize. At that state, they can then readily react with oxygen in the air, which gives off enough heat in the subsequent exothermic reaction to vaporize yet more fuel, thus sustaining a consistent flame. Sufficient energy in the flame will excite the electrons in some of the transient reaction intermediates which results in the emission of visible light as these substances release their excess energy. The chemical kinetics occurring in the flame is very complex and involves typically a large number of chemical reactions and intermediate species, most of them are radicals.
The challenge of the open candle flame simulation lies on the fidelity to resemble the subtle concept that candles burning with different flames have many different meanings and functions. The way that a candle burns can hold hidden significance as they can shine bright or glow dull in different situations like ceremonial, ritualistic, symbolic and utilitarian or all at the same time.
There have been some similar simulated candles in the technical field. For example, in U.S. Pat. No. 6,616,308, an imitation candle apparatus made from translucent material like paraffin having light transmissive properties is provided. Said imitation candle apparatus comprises a light diffusing body having permanent exterior surfaces including an upper surface with a depressed center section which appears reduced by melting, a cavity within the light diffusing body, and a small high density light source within the cavity to illuminate from below the bottom of the depressed center section more brightly than the other surfaces of the light diffusing body. It may have a light-sensing function which can turn the light off during day time and a flicker circuit which enables three to four distinct light levels that vary in a pseudo-random manner in order to provide a realistic variation of light output akin to a candle flame being disturbed by gentle air currents. Because the light source body of this patent is placed near the surface in the cavity and is from a small area, the light source is required to be super bright such that the light can be diffused throughout the body of the candle. It also can only vary the brightness level of the light source by varying the current to the LED under one or more low frequency oscillators. However, the light pattern of a candle flame cannot be simulated by that apparatus.
In U.S. Pat. No. 7,837,355, an apparatus creating flickering flame effect is provided including a housing incorporated with a time varying electromagnetic field driven mechanism to drive a first pendulum member with magnets on both ends in order to interact with the mechanism to generate a first pendulum movement followed by interacting with a second pendulum member having a magnet in order to generate a magnetic coupling effect on a flame silhouette extended from the second pendulum member. A light source is adapted to transmit light to the flame silhouette. The direction, magnitude, and frequency of the movement of the first and second pendulum members is limited by various factors including gravity, the magnitude and frequency of the time varying electromagnetic field for driving the mechanism, orientation of the magnet(s) on the first and second pendulum members, the mass, shape and size of the first and second pendulum members, any additional element intervening the movement of the pendulum, air resistance acting on the motion of the pendulum, etc. To drive the movement of the flame silhouette, that apparatus requires complex interactions between the drive mechanism, two pendulums, and any other intervening element, which makes it complicated in manufacturing and in operation.
In U.S. Pat. No. 8,070,319, which is under a continuation-in-part application of U.S. Pat. No. 7,837,355, it was further provided a single stage embodiment with one pendulum member, and an embodiment of a two-stage housing with a housing-contained lighting assembly and sidewall magnets for shaping and effecting movement of the flame body or the second pendulum member. According to one implementation method of the single stage embodiment, it was provided that there can be one or more than one light sources that may be aligned with each other. When the flame silhouette moves in normal operation with the connected pendulum member, its angle with respect to the light source(s) and the intensity of the reflected light changes continuously and in a complex, kinetic manner. In the two-stage embodiment, it was provided that the housing-contained lighting assembly can provide a beam of light about the size/shape of spot on the flame silhouette. It was also provided that the sidewall magnets are configured to provide a second kinetic movement to the upper pendulum member, in addition to the kinetic movement due to the interaction with the lower or first pendulum member resulted from the time-varying magnetic filed driven mechanism. The sidewall magnets can be modified in terms of the number of magnets, their position in the housing with respect to the upper pendulum member, their shape, etc., in order to result in a static magnetic field that interacts with the dynamic magnetic field to result in the desired movement of the flame body. The additional lighting assembly and sidewall magnets in the two-stage embodiment of this patent may provide enhanced lighting effect and motion patterns more resembling to an actual open flame, but still the problems are limited by the factors that are inherent from the magnetic field driven mechanism of the original design. The new embodiments in this patent are still complex in structure, leading to complications in manufacturing and operation.
In U.S. Pat. No. 8,342,712, which is a continuation-in-part application of U.S. Pat. No. 8,070,319, it was further provided a light engine controller to control at least two lighting devices/assemblies which provide light on opposite sides of the flame silhouette or on the same side thereof. The at least two lighting devices/assemblies can provide the same or different colors of light or can be monochromatic or multi-color light source. The light engine controller can control brightness or intensity of light from the lighting devices/assemblies and provide driving or control signals. The controller may include a processor and a power supply, wherein the processor may manage a memory containing flame lighting program that is executable by the processor to cause the processor to transmit control signals for driving or operating the various effects of the light source from the lighting devices/assemblies. The simulation algorithm(s) of the program according to different embodiments of this patent appear to be more focused on varying the brightness/intensity of the two lighting devices/assemblies in order to result in the desired coloring effect over time. Although the controller is said to be replaceable by manual controls, it appears that either the program pre-installed in the controller or manual controls is not capable to provide a corresponding visible light pattern to align with a reciprocal motion of the flame body with respect to air current flowing through the flame body. In other words, there is no correlation between the changing coloring effect and the motion of the flame body in this series of US patents.
Therefore, there is an unmet need in the art for a flameless candle resembling a burning candle with different flame patterns by sensing and responding to the change of the air current of its surroundings.